include/linux/seqlock.h

13  * - Sequence counters with associated locks, (C) 2020 Linutronix GmbH
27  * The seqlock seqcount_t interface does not prescribe a precise sequence of
48 	s->sequence = 0;  in __seqcount_init()
87 #define SEQCNT_ZERO(name) { .sequence = 0, SEQCOUNT_DEP_MAP_INIT(name) }
90  * Sequence counters with associated locks (seqcount_LOCKNAME_t)
92  * A sequence counter which associates the lock used for writer
105  * typedef seqcount_LOCKNAME_t - sequence counter with LOCKNAME associated
106  * @seqcount:	The real sequence counter
109  * A plain sequence counter with external writer synchronization by
110  * LOCKNAME @lock. The lock is associated to the sequence counter in the
160 	unsigned seq = READ_ONCE(s->seqcount.sequence);			\
170 		 * Re-read the sequence counter since the (possibly	\
173 		seq = READ_ONCE(s->seqcount.sequence);			\
211 	return READ_ONCE(s->sequence);  in __seqprop_sequence()
261 #define seqprop_sequence(s)		__seqprop(s, sequence)(s)
322  * masking the sequence counter LSB. Calling code is responsible for
383 	return unlikely(READ_ONCE(s->sequence) != start);
423 	s->sequence++;  in do_raw_write_seqcount_begin()
444 	s->sequence++;  in do_raw_write_seqcount_end()
477  * Context: sequence counter write side sections must be serialized and
566 	s->sequence++;  in do_raw_write_seqcount_barrier()
568 	s->sequence++;  in do_raw_write_seqcount_barrier()
587 	s->sequence+=2;  in do_write_seqcount_invalidate()
592  * Latch sequence counters (seqcount_latch_t)
594  * A sequence counter variant where the counter even/odd value is used to
626  * Return: sequence counter raw value. Use the lowest bit as an index for
636 	return READ_ONCE(s->seqcount.sequence);  in raw_read_seqcount_latch()
650 	return unlikely(READ_ONCE(s->seqcount.sequence) != start);  in raw_read_seqcount_latch_retry()
684  *		latch->seq.sequence++;
690  *		latch->seq.sequence++;
726  *	to miss an entire modification sequence, once it resumes it might
736 	smp_wmb();	/* prior stores before incrementing "sequence" */  in raw_write_seqcount_latch()
737 	s->seqcount.sequence++;  in raw_write_seqcount_latch()
738 	smp_wmb();      /* increment "sequence" before following stores */  in raw_write_seqcount_latch()
936  * locking readers, but it does not update the embedded sequence number.
1067  * Return: the encountered sequence counter value, through the @seq
1084  * @seq: sequence count, from read_seqbegin_or_lock()
1124  *   2. The encountered sequence counter value, returned through @seq